Constant capacity nozzle



F. G. SCHLOZ 3,053,462

Sept. 11, 1962 CONSTANT CAPACITY NOZZLE Filed Aug. 7, 1961 l 44 I 1 10 l3 '1 INVENTOR. immw/d die/71027,

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This application is a continuation-in-part of my patent application,Serial No. 87,595, filed February 7, 1961, entitled Constant CapacityNozzle, now abandoned.

This invention relates to fluid spray nozzles. By means of my invention,substantially constant flow rates are obtained regardless of changes influid viscosity.

While the nozzle of the present invention is principally used for fueloil, it may be used to handle other fluids, such as gasoline, waxes, waxemulsions, insecticides, vegetable oils, hot transformer oils, etc.Thus, while the new nozzle is particularly adapted for use onhigh-pressure domestic oil burners, it may also have other applications,such as in airplane heaters, jet engines, diesel engines, startingheaters, crop dryers, crop Sprayers, incubators, etc.

While, as just indicated, the nozzle of the present invention has otherapplications, it will be convenient to describe the new nozzle in itsapplication as a nozzle for a high-pressure gun-type domestic oilburner.

Domestic gun-type oil burners ordinarily operate at a fixed pressure offrom 75 to 200 psi, usually 100 psi. However, the capacity of theconventional prior-art nozzle, that is, the rate of discharge of thefuel oil from the orifice of the nozzle, varies with the 'viscosity ofthe fuel oil, the higher the viscosity, the greater being the nozzlecapacity or rate of discharge.

Stated another way, the conventional prior-art nozzle for a domestic oilburner is characterized by an inability to discharge oil at the samerate over the range of temperatures to which the burner is subjectedduring normal operation, this inability being a result of the fact thatthe viscosity of the oil changes with temperature. Thus, in \the usualthermostatically controlled domestic oil burner system, where the burneris repeatedly being turned on and off under the control of thethermostat, the rate at which the oil is discharged from the orifice ofthe nozzle at start-up, when the burner and fire box are relativelycold, is appreciably higher than the rate at which the oil is dischargedafter the burner and fire box become hot.

The fact that the rate of discharge is higher when the oil is cold andof higher viscosity may seem to be the reverse of that which would beexpected, but is explained by the fact that, in the conventional nozzleof a domestic oil burner, the oil is swirled about in a swirl chamberlocated inside the tip shell and is delivered from the discharge orificeof the nozzle in a swirling spinning manner, forming a cone-shaped spraypattern. The fuel oil when cold and of higher viscosity swirls in theswirl chamber at a substantially slower swirl rate than does the oilwhen hot and of substantially lower viscosity, and it has beenestablished that the rate of discharge from the orifice of the nozzle isinversely related to the swirl rate, the faster the oil is swirling inthe swirl chamber, the slower the rate of discharge from the orifice.

The fan and airrnixing equipment of the conventional domestic oil burnerare designed to deliver air at a substantially fixed rate. Thecombustion air and draft conditions are ordinarily adjusted for optimumfiring results after the fire box and burner have war-med up. Thus, itwill be seen that at start-up, when the fire box and burner arerelatively cold, and the oil being of higher viscosity is swirling at aslower rate and discharging at a faster rate, the fixed quantity of airprovided by the air 3,053,462 Patented Sept. 11, 1962 mixing equipmentis less than that required for optimum combustion, and thisinsufficiently of combustion air on start-up causes a smoky, sootycondition which is objectionable and which is avoided by the improvednozzle of the present invention.

The broad object of the present invention then is to provide a fluidspray nozzle capable of discharging fluid at a substantially constantrate irrespective of the viscosity of the fluid, within the operatingrange of the device.

It is another object of the present invention to provide a nozzle for afuel oil burner which discharges fuel oil at a substantially constantrate irrespective of changes in the viscosity of the fuel oil due tovariations in the operating temperature, or due to any other cause, suchas varia' tions in the grade of the fuel oil.

A more specific object is to provide a constant capacity nozzle for adomestic oil burner capable of discharging fuel oil at a substantiallyconstant rate despite variations in the viscosity of the oil.

Another object of the invention is to provide a spray nozzle which willdischarge fluid at a substantially constant spray angle irrespective ofthe viscosity of the fluid.

A more specific object is to provide a spray nozzle for a domestic oilburner which will discharge fuel oil at a substantially constant rateand at a substantially constant spray angle irrespective of variationsin the viscosity of the fuel oil.

The above and other objects and advantages of the present invention areaccomplished by a nozzle construction in which the swirl-impartingmember or disk carries the swirl slots well into the swirl chamber, withthe swirl slots so positioned that their inner edges are outside theprojected diameter of the orifice by a small dimension. Thisconstruction, which will be better understood after the detaileddescription which follows is read, has been found to produce astabilized rate of flow, the nozzle discharging fluid at substantiallythe same rate irrespective of its viscosity.

The invention will be more clearly understood from a consideration ofthe following detailed description of a preferred embodiment illustratedin the drawing, in which:

FIG. 1 is a side elevational view, mainly in section, of one formv ofthe improved nozzle;

FIG. 2 is a top or end view, partly in section, of the improved nozzleof FIG. 1;

FIG. 3 is an enlarged view, partly in section, of the end portion of thenozzle of FIG. 1 showing the discharge orifice, the swirl chamber, andthe swirl disk having swirl slots entering into the swirl chamber; and

FIG. 4 is a view in section along the line IV-IV of FIG. 3 looking inthe direction of the arrows.

In describing the preferred embodiment of the invention illustrated inthe drawing, specific terminology has been resorted to for the sake ofclarity. However, it is not my intention to be limited to the specificterms 50 selected, and it is to be understood that each specific termincludes all technical equivalents which operate in a similar manner toaccomplish a similar purpose.

Referring now to the drawing, the nozzle illustrated includes aconventional hollow tip shell 10 and a conventional hollow adapter 12.The tip shell 10 may preferably be of stainless steel while adapter 12may preferably be of brass.

The tip shell 19 comprises an upper rounded portion 14, a hexagonalcenter portion 16, and a lower externally threaded portion 18. Roundedportion 14 is flattened at the top and is provided with the usual smallcylindrical orifice 20 which connects the hollow interior of the tipshell 10 to the exterior of the shell and functions as the dis chargeorifice for the fuel oil or other fluid. The center portion 16 has ahexagonal exterior to facilitate tightening or loosening of the tipshell by a tool. Portion 18 is threaded externally for receiving theadapter 12 and is threaded internally for receiving a lock-nut 22 and astrainer support 26.

Adapter 12 has an upper larger bore and a lower smaller bore, both boresbeing threaded internally. The upper portion of the threaded upper boreis adapted to engage with the externally-threaded portion 18 of the tipshell 10. The lower portion of the upper larger bore of adapter 12 isadapted to receive the usual hollow cylindrical strainer screen 24suitably supported by the strainer support 26 containing feed slots 26a.Strainer support 26 is provided at its upper end with external threadsfor engagement with the lower internal threads of the portion 18 of tipshell 10, thereby providing a space or passage between the inner surfaceof the lower portion of the upper bore and the cylindrical strainerscreen 24. The lower end of strainer support 26 is solid.

The smaller lower bore of adapter 12 is for receiving the fuel-supplypipe which connects the nozzle to the fuel supply.

As seen in FIGS. 1 and 3, the hollow interior of the tip shell 10, whichis conventional, is characterized by a first frusto-conical swirlchamber 30 just below the cylindrical axial discharge orifice 10, asecond frusto-conical diskseating chamber 32 below the swirl chamber 30,and a cylindrical chamber 34 below the second frusto-conical chamber 32.The slope of the wall of the swirl chamber 30 is substantially steeperthan that of the wall of the diskseating chamber 32. In the absence ofthe swirl disk 40, described below, the lower limit of swirl chamber 30would be an imaginary horizontal plane which coincides with the plane ofthe upper limit of chamber 32, this plane being identified in FIG. 3 bythe dotted line 36. However, when the swirl disk 40 is in place andseated, as is the case when the nozzle is assembled for use, the flooror bottom of the swirl chamber 30 also has a frusto-conicalconfiguration which is different in shape from the frusto-conical topportion of the swirl chamber. It will be understood that thefrusto-conical floor or bottom portion of swirl chamber 30 is formed bythe upper portion of the swirl disk 40.

Swirl disk 40 is a solid, frusto-conical disk, preferably of stainlesssteel, which is fitted into the top of a hollow cylindrical holder 42,which may be of brass. Holder 42 is provided near its lower end with apair of opposed holes 44, 46 which extend completely through the wall ofthe holder. The outside diameter of holder 42 is smaller than the insidediameter of chamber 34, thus providing an annular space or passage forthe oil or other fluid which fiows out through the holes 44, 46, as willbe described.

Swirl disk 40 and holder 42 are supported by the locknut 22 previouslymentioned. Lock-nut 22 is T-shaped, its larger upper portion beingexternally threaded for engagement with the internal threads of portion18 of the tip shell 10. The smaller lower portion of lock-nut 22 isprovided with a slot for facilitating turning by a tool. Lock-nut 22 isprovided with an axial bore which extends completely therethroughthereby providing communication for fluid flow between the interior ofthe strainer support 26 and the hollow interior of the disk holder 42.

Described in greater detail, swirl disk 40 has a solid cylindrical lowerportion which fits into and is received by the hollow upper portion ofthe holder 42. The upper portion of swirl disk 40 is solid andfrusto-conical, the base portion thereof being of slightly largerdiameter than the depending cylindrical portion which fits into theholder 42. The conical portion slopes upwardly at an angle equal to thatof the slope of inner wall of frustoconical chamber 32 so that when thelock-nut 22 is turned in a direction to move the lock-nut upward in thetip shell 10, the surface of the frusto-eonical portion of the swirldisk 40 seats against, i.e., makes wide band contact with, the wall ofchamber 32.

The surface of the frusto-conical portion of swirl disk 40 is providedwith one or more, usually four, straight swirl slots which are milled orotherwise cut in the frustoconical surface and which extend from thelower edge of the frusto-conical portion to the upper edge. Four suchswirl slots are shown in the drawing identified by the referencenumerals 48a, 48b, 48c and 48d.

The location of the swirl slots in the sloping surface of thefrusto-conical portion of disk 40 is such that when the disk 4% isviewed from the top or end, as in FIGS. 2 and 4, the swirl slots appearto be at right angles to each other with the inner edge of each slot(i.e. the edge nearer to the projected diameter of orifice 20) beingclose to but outside of the projected diameter of orifice 20. -Aspecific example of this structural arrangement is illustrated in FIGS.3 and 4 where the orifice 29 (FIG. 3) is shown as having a diameter of.011 inch while the distance between the projected inner edges ofopposite slots 48!; and 48d is shown as being .013 inch. Thus, the inneredge of each of the slots 48!) and 43d is outside of the projecteddiameter of orifice 20 (illustrated by the dot-and-dash circle 20a inFIG. 4) by .001 inch. This last small dimension (.001") is not shown toscale in the drawing in order to show clearly that the inner edges ofthe slots are outside of the projected diameter of the orifice.

The same dimensions shown for slots 48b and 48d also apply to the otherpair of opposite slots 48a and 48c.

Stated more generally, the swirl slots 48a, 48b, 48c and 48d enter theswirl chamber 30 on a diameter slightly larger than the diameter of theprojected orifice, where the diameter of entry of the slots is definedas the distance between inner edges of opposite slots, .013 in theillustrated example. Thus, in the example illustrated, the slots enterthe swirl chamber 30 on a diameter of .013" as compared with an orificediameter of .011.

It is to be noted that opposing slots, such as 48a, 480, are not axiallyaligned, but are off-set from each other. Thus, the slots 48 aretrangential to the swirl chamber 30. When the disk 40 is viewed from theside in elevation as in FIGS. 1 and 3, the four swirl slots 48a, 48b,48c and 48d are of course, seen to slope upwardly and inwardly,following the slope of the frustoconical portion of swirl disk 40.

It is also to be noted that in the constant capacity nozzle of thepresent invention the frusto-conical portion of the swirl disk 40 issized and shaped to carry the swirl slots above the lower limit 36 ofthe wall of the swirl chamber 30. Stated another way, the swirl slotsare carried above the uppermost line of contact between the wall of thechamber 32 and the wall of the swirl disk 40, and thus may be said to becarried well into the swirl chamber 36.

In operation, fuel oil from the source of supply is fed into the nozzleby way of the lower bore of the adapter 12 in the direction of the arrowin FIG. 1. "The fuel oil is fed at substantially fixed pressure, in therange of from 75 to 200 psi. ordinarily about psi, and flows through thelower bore of adapter 12 into the annular space between the strainer 24and the wall of the larger bore of the adapter 12, then through thescreen of strainer 24 in the direction from outside the strainer screenthrough the feed slots 26a to the interior of the strainer support 26,up through the bore of the lock-nut 22 into the bore of disk holder 42,out through holes 44, 46 in the disk holder 42, up through the spacebetween the outer wall of the disk holder 42 and the inner surface ofthe cylindrical chamber 34, up through the swirl slots 48a, 48b, 48c,and 48d into the swirl chamber 30, and out through discharge orifice 20.As the fuel oil (or other fluid) is forced under pressure out of theswirl slots 48a, 48b, 43c, and 48d and into the frusto-conical swirlchamber 30, the oil is caused, by the tangential positions of the swirlslots relative to the swirl chamber 30, to swirl about within thechamber 30. The oil continues to swirl as it passes through the orifice20', and is discharged therefrom in a spinning swirling atomized sprayof cone configuration.

While the reasons are not fully understood, when the swirl slots arecarried well into the swirl chamber on a diameter slightly larger thanthat of the projected orifice, .013 inch versus .011 inch in theillustrated example, the rate at which the fuel oil (or other fluid)swirls about within the swirl chamber 30 apparently becomes independentof the viscosity of the oil. In any event, when this construction isused, the nozzle becomes characterized by the ability to discharge oil(or other fluid) at a constant rate irrespective of the viscosity of thefluid, within the range of operation of the nozzle. In other words, whenthe construction of the nozzle is changed from one in which the swirlducts terminate at or below the lowermost limit of the wall of the swirlchamber to one in which the swirl ducts extend well into the swirlchamber, on a diameter slightly larger than that of the orifice, asdescribed above, the nozzle becomes converted from one whose capacityvaries with viscosity to one of substantially constant capacity over therange of viscosities for which the nozzle is intended to operate.

The following is an illustration of the improvement afforded by the newnozzle of the present invention. Tests have shown that the capacity(i.e. the rate of fluid discharge) of the prior art nozzle will vary asmuch as 20 to 25 percent between the extremes of cold oil at 5060 F. andhot oil at about 250 F., these being the temperature ranges ordinarilyencountered in domestic oil burner operation. "Stated in terms ofkinematic viscosity, this represents a variation of from about 4.3centistokes when cold, to about 0.85 centistokes when hot.

Whereas the prior-art nozzles vary in capacity by as much as 20-25percent during operation between the above stated extremes oftemperature and viscosity, the nozzle of the present invention has beenfound to vary by only about 2 percent. Thus, the improved nozzle may besaid to be a nozzle of substantially constant capacity over the expectedoperating range of temperatures and viscosities. As a result, theobjectionable sooting which characterizes the prior-art burner atstart-up is avoided.

In addition to being characterized by the ability to discharge fuel oilor other fluid at a substantially constant capacity, the new nozzleproduces cone sprays having spray angles which are substantiallyconstant with varying viscosity of fuel oil or other fluid. This is alsoa highly desirable operating characteristic.

The exact relative dimensions or proportions of such things as size oforifice, size and shape of swirl chamber, size and shape of disk seatand disk-seat chamber, number and size of swirl slots, etc., will varywith desired nozzle capacity. The following is one specific example ofnozzle dimensions which have been found to produce a constant capacitynozzle for #2 fuel oil having a rating of 1.00 gallon per hour (g.p.h.)at 100 p.s.i. The discharge orifice of 0.011". The swirl chamber has afrusto-conical top portion and a frusto-conical floor formed by thedisk. The swirl chamber has a maximum diameter of 0.060" and an includedangle of 84. The frusto-conical seat of the swirl disk has an includedangle of 120, and four feed slots each 0.007" square. The feed slotsenter the swirl chamber on a diameter of .013, as defined hereinbefore,the inner edges of opposite slots being .013" apart. Tests have shownthat when a 1.00 g.p.h. nozzle having the above dimensions is used todischarge #2 fuel oil at 100 p.s.i. over a temperature variation from 50F. to 250 F., which is equivalent to a viscosity variation of from 4.3centistokes to .85 centistokes, the variation in rate of discharge isonly 0.02 g.p.h., or about 2 percent. Using the same grade of oil andover the same range of temperatures, the capacities of prior art nozzleswere 6 found to vary between 18.5 and 27.0 percent. On some sizes of thenew nozzle, the variation in capacity is only 0.002 g.p.h. when thetemperature is varied :firom 50 F. to 250 F.

While the preferred embodiment of this invention has been described insome detail, it will be obvious to one skilled in the art that variousmodifications may be made without departing from the invention ashereinafter claimed.

Having described my invention, I claim:

1. A fluid spr-ay nozzle comprising a tip shell having an orifice, aninternal frusto-conical swirl chamber and an internal disk seatingchamber, a frusto-conical swirl disk mounted internally and seated insaid disk seating chamber and formed with one or more feed slots, saidswirl chamber having a concave frusto-conical base portion when saiddisk is seated in said disk seating chamber, said feed slots enteringsaid swirl chamber on a diameter just sufliciently larger than theprojected diameter of said orifice to bring the projected inner edges ofsaid feed slots outside said projected diameter of said orifice by adistance substantially less than the diameter of said orifice.

2. A fluid spray nozzle comprising a tip shell having an orifice, aninternal frusto-conical swirl chamber and an internal disk seatingchamber, a frusto-conical swirl disk mounted internally and seated insaid disk seating chamber so as to extend substantially into the swirlchamber and formed with one or more feed slots, said swirl chamber beingof frusto-conical shape at each end when said disk is seated in saiddisk seating chamber, said feed slots entering said swirl chamber on adiameter just sufliciently larger than the projected diameter of saidorifice to bring the projected inner edges of said feed slots outsidesaid projected diameter of said orifice by a distance substantially lessthan the diameter of said orifice.

3. A fluid spray nozzle comprising a tip shell having an orifice, aninternal frusto-conical swirl chamber and an internal disk seatingchamber, a frusto-conical swirl disk mounted internally and seated insaid disk seating chamber so as to extend substantially into the swirlchamber and formed with a plurality of feed slots carried by said disksubstantially within the swirl chamber, said swirl chamber having adished frusto-conical base portion when said disk is seated in said diskseating chamber, said feed slots entering said swirl chamber on adiameter just sufliciently larger than the projected diameter of saidorifice to bring the projected inner edges of the feed slots outsidesaid projected diameter of said orifice by a distance substantially lessthan the diameter of said orifice.

4. A fluid spray nozzle comprising a tip shell having an orifice, aninternal swirl chamber and an internal disk seating chamber, a swirldisk mounted internally and seated in said disk seating chamber so as toextend substantially into the f-rusto-conical swirl chamber and formedwith one or more feed slots carried by said disk substantially withinthe swirl chamber, said swirl chamber formed by two adjacentnon-congruent frusto-conical shapes when said swirl disk is seated insaid disk seating chamber, said feed slots entering said swirl chamberon a diameter just sufficiently larger than the projected diameter ofsaid orifice to bring the projected inner edges of the feed slotsoutside said projected diameter of said orifice by a distancesubstantially less than the diameter of said orifice.

5. A fluid spray nozzle comprising a tip shell having an orifice, aninternal frusto-conical swirl chamber and an internal disk seatingchamber, a frusto-conical swirl disk seated within said disk seatingchamber and extending substantially int-o the swirl chamber but withoutcontacting the wall of said swirl chamber, a plurality of feed slots inthe surface of said disk, a portion of said feed slots extending intosaid swirl chamber without contact thereof, said swirl chamber beingformed by two adjacent noncongruent frusto-conical shapes when saidswirl disk is seated within said disk seating chamber, said feed slotsentering said swirl chamber on a diameter just sufficiently larger thanthe projected diameter of said orifice to bring the projected inneredges of the feed slots outside said projected diameter of said orificeby a distance substantially less than the diameter of said orifice.

6. A fluid spray nozzle comprising a tip shell having an orifice, aninternal swirl chamber and an internal disk seating chamber, afrusto-conical swirl disk mounted internally and seated in said diskseating chamber so as to extend substantially into the swirl chamber andformed with one or more feed slots carried by said disk substantiallywithin the swirl chamber, said swirl chamber being of frusto-conicalshape at each end when said swirl disk is seated in said disk seatingchamber, said feed slots entering said swirl chamber on a diametersufiiciently larger than the projected diameter of said orifice to bringthe inner edges of the feed slots outside said projected diameter ofsaid orifice by a distance substantially less than the diameter of saidorifice.

7. A fluid spray nozzle comprising: a tip shell having an orifice, aninternal swirl chamber and an internal diskseating chamber; a swirl diskseated in said disk-seating chamber and having at one end afrusto-conical portion extending into said swirl chamber, said swirlchamber having a frusto-conical shape with the small diameter endcommunicating with said orifice, said swirl chamber also having afrusto-conical floor formed by the frusto-conical portion of said swirldisk, said swirl disk having in the surface of its frusto-conicalportion a plurality of swirl slots so positioned that said swirl slotsenter said swirl chamber on a diameter sufliciently larger than thediameter of said orifice projected onto the face of said frusto conicalportion of said swirl disk so that the inner edges of said slots arejust outside said projected diameter of said orifice by a distancesubstantially less than the diameter of said orifice.

8. A fluid spray nozzle as claimed in claim 7 adapted for discharging #2fuel oil at 1.00 gallon per hour (average) at 100 pounds per squareinch, characterized in that said orifice has a diameter of .011 inch andin that said swirl slots are so located as to enter said swirl chamberon a diameter of .013 inch.

9. A fluid spray nozzle as claimed in claim 7 characterized in that saidswirl slots enter said swirl chamber on a diameter just suificientlylarger than the diameter of said orifice projected onto the face of saidfrusto-conical portion of said swirl disk so that the projected inneredges of said slots are outside said projected diameter of said orificeby a distance which is of the order of thirty percent or less of thediameter of said orifice.

References Cited in the file of this patent UNITED STATES PATENTS1,896,744 Frick Feb. 7, 1933 1,982,228 Murphy Nov. 27, 1934 2,071,920Czarnecki Feb. 23, 1937 FOREIGN PATENTS 20,199 Great Britain of 1891UNITED STATES PATENT CERTIFICATE OF CORRECTION Patent No, 3,053,462September 11, 1962 Ferdinand G. .Schloz It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 6, line 55 strike out "frust;conical" and insert same before"swirl disk", in line 53, same column 6.

Signed and sealed this 19th day of February 1968 (SEAL) Attest:

ESTON G, JOHNSON DAVID L. LADD Attesting Officer I Commissioner ofPatents

